Evaluation of medicinal plant extracts and isolated compound epicatechin from Ricinus communis against Paramphistomum cervi.

The purpose of this study is to determine the efficacies of hexane, chloroform, ethyl acetate, acetone, and methanol leaf extracts of Euphorbia hirta L., Psidium guajava L., Ricinus communis L., Solanum trilobatum L., and Tridax procumbens L. against sheep fluke Paramphistomum cervi (Digenea: Paramphistomatidae). All plant extracts showed moderate effects after 24 h of exposure; however, the highest parasite mortality was found in the methanol extract of R. communis. In the present study, bioassay-guided fractionation of methanol extract of R. communis led to the separation and identification of epicatechin as a potential new compound (LC(50) = 31.2; LC(90) = 105.0 ppm) against P. cervi. The structures were established from infrared, ultraviolet, (1)H-nuclear magnetic resonance (NMR), (13)C-NMR, and mass spectral data which confirmed the identification of the compound epicatechin from R. communis. Results of this study showed that the methanol extract of R. communis may be considered as a potent source and epicatechin as a new natural parasitic agent.

Mosquito larvicidal activity of isolated compounds from the rhizome of Zingiber officinale.

The larvicidal activity of a petroleum ether extract of Zingiber officinale Roscoe (Zingiberaceae) was evaluated against Aedes aegypti L. and Culex quinquefasciatus Say (Diptera). Bioassay-guided fractionation led to the isolation of 4-gingerol (1), (6)-dehydrogingerdione (2) and (6)-dihydrogingerdione (3); the latter has not previously been reported from Z. officinale. The structures were established from infrared (IR), ultraviolet (UV), (1)H-nuclear magnetic resonance (NMR), (13)C-NMR and mass spectral data. Following a 24 h exposure, compounds 1-3 exhibited larvicidal activities against fourth instar larvae of A. aegypti (LC(50) 4.25, 9.80, 18.20 ppm) and C. quinquefasciatus (LC50 5.52, 7.66, 27.24 ppm), respectively. The results show that the most effective compound was 4-gingerol.

Larvicidal activity of saponin from Achyranthes aspera against Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae).

The acetone, chloroform, ethyl acetate, hexane and methanol leaf extracts of Acalypha indica, Achyranthes aspera, Leucas aspera, Morinda tinctoria and Ocimum sanctum were studied against the early fourth-instar larvae of Aedes aegypti L and Culex quinquefasciatus Say. The larval mortality was observed after 24 h exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in the ethyl acetate extract of A. aspera. In the present study, bioassay-guided fractionation of A. aspera led to the separation and identification ofa saponin as a potential mosquito larvicidal compound, with LC50 value of 18.20 and 27.24 ppm against A. aegypti and C. quinquefasciatus, respectively. 1H NMR, 13C NMR and mass spectral data confirmed the identification of the active compound. This is the first report on the mosquito larvicidal activity of the saponin from the ethyl acetate extract of A. aspera. This study investigates the potential of crude extracts from commonly used medical herbs in India as an environmentally safe measure to control the vector of dengue and lymphatic filariasis.

Mosquito larvicidal activity of gluanol acetate, a tetracyclic triterpenes derived from Ficus racemosa Linn.

The larvicidal activity of crude hexane, ethyl acetate, petroleum ether, acetone, and methanol extracts of the leaf and bark of Ficus racemosa (Moraceae) was assayed for their toxicity against the early fourth-instar larvae of Culex quinquefasciatus (Diptera: Culicidae). The larval mortality was observed after 24-h exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in bark acetone extract of F. racemosa. In the present study, bioassay-guided fractionation of acetone extract led to the separation and identification of a tetracyclic triterpenes derivative; gluanol acetate was isolated and identified as new mosquito larvicidal compound. Gluanol acetate was quite potent against fourth-instar larvae of Aedes aegypti L. (LC(50) 14.55 and LC(90) 64.99 ppm), Anopheles stephensi Liston (LC(50) 28.50 and LC(90) 106.50 ppm) and C. quinquefasciatus Say (LC(50) 41.42 and LC(90) 192.77 ppm). The structure was elucidated from infrared, ultraviolet, (1)H-nuclear magnetic resonance (NMR), (13)C-NMR, and mass spectral data. This is the first report on the mosquito larvicidal activity of the reported compound from F. racemosa.

Isolation and identification of mosquito larvicidal compound from Abutilon indicum (Linn.) Sweet.

Larvicidal activity of crude hexane, ethyl acetate, petroleum ether, acetone and methanol extracts of five medicinal plants, Abutilon indicum, Aegle marmelos, Euphorbia thymifolia, Jatropha gossypifolia and Solanum torvum were assayed for their toxicity against the early fourth-instar larvae of Culex quinquefasciatus. The larval mortality was observed after 24 h exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in petroleum ether extract of A. indicum. In the present study, bioassay-guided fractionation of A. indicum led to the separation and identification of a beta-sitosterol as a potential new mosquito larvicidal compound with LC50 value of 11.49, 3.58 and 26.67 ppm against Aedes aegypti L, Anopheles stephensi Liston and C. quinquefasciatus Say (Diptera: Culicidae), respectively. 1H NMR, 13C NMR and mass spectral data confirmed the identification of the active compound. beta-sitosterol has been recognized as the active ingredient of many medicinal plant extracts. All the crude extracts when screened for their larvicidal activities indicated toxicity against the larvae of C. quinquefasciatus. This article reports the isolation and identification of the beta-sitosterol as well as bioassay data for the crude extracts. There are no reports of beta-sitosterol in the genus A. indicum, and their larvicidal activities are being evaluated for the first time. Results of this study show that the petroleum ether extract of A. indicum may be considered as a potent source and beta-sitosterol as a new natural mosquito larvicidal agent.

Larvicidal activity of some Euphorbiaceae plant extracts against Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae).

Larvicidal activity of ethyl acetate, butanol, and petroleum ether extracts of five species of Euphorbiaceae plants, Jatropha curcas, Pedilanthus tithymaloides, Phyllanthus amarus, Euphorbia hirta, and Euphorbia tirucalli, were tested against the early fourth instar larvae of Aedes aegypti L. and Culex quinquefasciatus (Say). The larval mortality was observed after 24 h of exposure. All extracts showed low larvicidal effects; however, the highest larval mortality was found in petroleum ether extract. The LC50 value of petroleum ether extracts of J. curcas, P. tithymaloides, P. amarus, E. hirta, and E. tirucalli were 8.79, 55.26, 90.92, 272.36, and 4.25 ppm, respectively, against A. aegypti and 11.34, 76.61, 113.40, 424.94, and 5.52 ppm, respectively, against C quinquefasciatus. Of the various ratios tested, the petroleum ether extracts of J. curcas and E. tirucalli were observed to be more efficient than the other plant extracts. It is, therefore, suggested that E. tirucalli can be applied as an ideal potential larvicide against A. aegypti and C. quinquefasciatus. This is an ideal ecofriendly approach for the control of the dengue vector, A. aegypti, and the lymphatic filariasis vector, C. quinquefasciatus.